Audio Amplifier without transistors or tubes?

[jacquesl]

Hi,

Is it possible to build a small amp or a big amp without the need of any semiconductors or tubes?
Just plain old coils, caps, Resistors or any homemade switching conductors.

And here I have a mystery question, is it possible to change the impedance of a coil by disturbing it with a other magnetic field or something? Like in a transformer


I think this project will be must easier to build then my “Transmitters without transistors or Tubes”
http://www.diyaudio.com/forums/showthread.php?s=&threadid=90980


check out a picture of a MJ2955 Transistor slashed open

 

[djQUAN]

I have seen from a '60s magazine a schem of a 1kW switching amplifier which uses special switching diodes and trasformers.

it does use semiconductors but no transistors or tubes.

 

[lumanauw]

Hi, jacquesl

Why do you want to advoid transistor/tubes? I'm not allergic to transistors, but still looking for a more linear transistor (if possible, have linearity like simple plain resistor supplied with current )

I'm not thinking about how to do it, but from the word "Amplifier" it means a device to "amplify".
How do you make an "amplifier" without a device to "amplify" anything?

 

[heater]

Jacquesl, this time you may be lucky, check out magnetic amplifiers, there is a scan of a book on this here:http://www.pmillett.com/tecnical_books_online.htm

 

[jacquesl]

Yo, thanks heater, this is some ultra good stuff man.
Do you think magnetic amplifiers can deliver some good quality sound and the other part will it cause some serous magnetic interferences with my other stuff, like to give some free bad sectors to my Hard drives and cause my TV to change the image to weird shapes and colours

 

[jacquesl]

Is there any way to make a switch with a transformer?

I see this transformer even have a Bias on him

 

[Christer]

Is there any way to make a switch with a transformer?

I see this transformer even have a Bias on him

Not quite transformers, but there are relays. I suppose one could build a very-low-frequency class D amp using relays instead of transistors.

 

[jacquesl]

I don’t know if relays will do the job “It probably depends on the load, It will make some serous noise like click click click click and it will cause a interference on the TV and on AM radio it will act like a spark gap transmitter.

 

[Christer]

I don’t know if relays will do the job “It probably depends on the load, It will make some serous noise like click click click click and it will cause a interference on the TV and on AM radio it will act like a spark gap transmitter.

It would need heavy filtering, and note that I said ver low frequencies. That was mainly because relays are slow, but it will also help to filter out sparks, since they will produce very high frequencies in comparison to the signal. As for the mechanical noise, yes that might be a problem, but I suppose this was rather about what one could possibly do than what might provide a good alternative to standard technology.

 

[jacquesl]

Yip your 100% correct. Well lets start a project like this and see if we can out perform the transistor and maybe come up with a new technology and maybe we can win a Nobel prize one day

 

[heater]

I find the whole idea of magnetic amplifiers fasinating and might have to do a simple experiment with a saturable core just to see it workiing at all. However this seems to have no chance for audio, see here for why: http://www.tpub.com/content/neets/14180/css/14180_131.htm

 

[martin clark]

I know Per Lundahl - the founder of the magnetics company - has experimented with magnetic amplifiers for a long time. They run seriously hot, and are pretty inefficient, but I remember reading a comment by UK reviewer Paul Messenger saying prototypes had an incredible clarity, especially at low listening levels.

That was seven or eight years ago, I don't what became of the project.

 

[heater]

I'd love to know what Per Lundahl did because mag amps have always been noted as very efficient, they are/were used to control thousands of watts, but no good at low levels. Not to mention the huge distortion.

In fact in those old papers I have linked to I get the idea of huge power gain but the control input is basically DC whilst the power being controlled is AC.

Given the reputation of Per's audio transformers if he can't get it to work nicely then nobody can.

 

[martin clark]

IIRC there was something in the article about using 4-quadrant control to get around the ditortion issue, so it's probably a trade-off against efficiency. If I can find the magazine article I'll scan it and post a link.

 

[el`Ol]

A magamp by Lundahl had been on the market for some time in the 90ies and got good reviews. There was a simplified schematic in a German hifi magazine. Unfortunately I threw it away and I also can`t find it in the web.

 

[martin clark]

Here's teh one I was thinking of - Markus Sauer (not Paul Messenger) writing in Stereophile , September 1998:

http://www.acoustica.org.uk/misc/lundahl-1.jpg
http://www.acoustica.org.uk/misc/lundahl-2.jpg
http://www.acoustica.org.uk/misc/lundahl-3.jpg

(low-res scans, about 350KB /page)

 

[jacquesl]

http://www.tpub.com/content/neets/14180/css/14180_139.htm

A Simple Example, working on a Toroidal transformer

 

[myhrrhleine]

You could make an amp out of many things, even water using faucets.
Tubes/transistors are just easier.

Use the tool that works best for you.

 

[poynton]

It ain't so !!!

HI.

Reading the article carefully reveals that the following are required :-

A line level input stage.
A voltage to pulse width converter
A choke driver stage

So hardly without tubes or transistors.

It would also appear to require a special loudspeaker tailored to the amplifiers strange characteristics.

Andy

 

[lineup]

Museum of RetroTechnology - by Douglas Self

.

A Hot-Air Engined Gramophone.

This remarkable gramophone is powered by a hot-air engine instead of the usual clockwork. It was found at the National Gin Museum in Hasselt, Belgium.

The link there is that the engine is heated by alcohol.
It was called "The Maestrofoon",
and according to the label on the case,
was made by Paillard in Switzerland, around 1915.

Hot-Air Gramophone web page

Table of Contents

Pneumatic Networking
A Hot-Air Engined Gramophone
The Fluidic Gramophone
Compressed-Air Amplifiers
Mechanical Amplifiers
ElectroMechanical Amplifiers
Early Telephone Lines
Optical Telegraphs
Voicepipes & Speaking Tubes
Heliographs

The Museum of RetroTechnology - by Douglas Self (audio amplifier man)



Web Research
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lineup